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#[cfg(feature = "metadata-name")]
use core::cell::Cell;
use core::future::{Future, poll_fn};
#[cfg(feature = "scheduler-priority")]
use core::sync::atomic::{AtomicU8, Ordering};
use core::task::Poll;
#[cfg(feature = "metadata-name")]
use critical_section::Mutex;
use crate::raw;
#[cfg(feature = "scheduler-deadline")]
use crate::raw::Deadline;
/// Metadata associated with a task.
pub struct Metadata {
#[cfg(feature = "metadata-name")]
name: Mutex<Cell<Option<&'static str>>>,
#[cfg(feature = "scheduler-priority")]
priority: AtomicU8,
#[cfg(feature = "scheduler-deadline")]
deadline: raw::Deadline,
}
impl Metadata {
pub(crate) const fn new() -> Self {
Self {
#[cfg(feature = "metadata-name")]
name: Mutex::new(Cell::new(None)),
#[cfg(feature = "scheduler-priority")]
priority: AtomicU8::new(0),
// NOTE: The deadline is set to zero to allow the initializer to reside in `.bss`. This
// will be lazily initalized in `initialize_impl`
#[cfg(feature = "scheduler-deadline")]
deadline: raw::Deadline::new_unset(),
}
}
pub(crate) fn reset(&self) {
#[cfg(feature = "metadata-name")]
critical_section::with(|cs| self.name.borrow(cs).set(None));
#[cfg(feature = "scheduler-priority")]
self.set_priority(0);
// By default, deadlines are set to the maximum value, so that any task WITH
// a set deadline will ALWAYS be scheduled BEFORE a task WITHOUT a set deadline
#[cfg(feature = "scheduler-deadline")]
self.unset_deadline();
}
/// Get the metadata for the current task.
///
/// You can use this to read or modify the current task's metadata.
///
/// This function is `async` just to get access to the current async
/// context. It returns instantly, it does not block/yield.
pub fn for_current_task() -> impl Future<Output = &'static Self> {
poll_fn(|cx| Poll::Ready(raw::task_from_waker(cx.waker()).metadata()))
}
/// Get this task's name
///
/// NOTE: this takes a critical section.
#[cfg(feature = "metadata-name")]
pub fn name(&self) -> Option<&'static str> {
critical_section::with(|cs| self.name.borrow(cs).get())
}
/// Set this task's name
///
/// NOTE: this takes a critical section.
#[cfg(feature = "metadata-name")]
pub fn set_name(&self, name: &'static str) {
critical_section::with(|cs| self.name.borrow(cs).set(Some(name)))
}
/// Get this task's priority.
#[cfg(feature = "scheduler-priority")]
pub fn priority(&self) -> u8 {
self.priority.load(Ordering::Relaxed)
}
/// Set this task's priority.
#[cfg(feature = "scheduler-priority")]
pub fn set_priority(&self, priority: u8) {
self.priority.store(priority, Ordering::Relaxed)
}
/// Get this task's deadline.
#[cfg(feature = "scheduler-deadline")]
pub fn deadline(&self) -> u64 {
self.deadline.instant_ticks()
}
/// Set this task's deadline.
///
/// This method does NOT check whether the deadline has already passed.
#[cfg(feature = "scheduler-deadline")]
pub fn set_deadline(&self, instant_ticks: u64) {
self.deadline.set(instant_ticks);
}
/// Remove this task's deadline.
/// This brings it back to the defaul where it's not scheduled ahead of other tasks.
#[cfg(feature = "scheduler-deadline")]
pub fn unset_deadline(&self) {
self.deadline.set(Deadline::UNSET_TICKS);
}
/// Set this task's deadline `duration_ticks` in the future from when
/// this future is polled. This deadline is saturated to the max tick value.
///
/// Analogous to `Timer::after`.
#[cfg(all(feature = "scheduler-deadline", feature = "embassy-time-driver"))]
pub fn set_deadline_after(&self, duration_ticks: u64) {
let now = embassy_time_driver::now();
// Since ticks is a u64, saturating add is PROBABLY overly cautious, leave
// it for now, we can probably make this wrapping_add for performance
// reasons later.
let deadline = now.saturating_add(duration_ticks);
self.set_deadline(deadline);
}
/// Set the this task's deadline `increment_ticks` from the previous deadline.
///
/// This deadline is saturated to the max tick value.
///
/// Note that by default (unless otherwise set), tasks start life with the deadline
/// not set, which means this method will have no effect.
///
/// Analogous to one increment of `Ticker::every().next()`.
///
/// Returns the deadline that was set.
#[cfg(feature = "scheduler-deadline")]
pub fn increment_deadline(&self, duration_ticks: u64) {
let last = self.deadline();
// Since ticks is a u64, saturating add is PROBABLY overly cautious, leave
// it for now, we can probably make this wrapping_add for performance
// reasons later.
let deadline = last.saturating_add(duration_ticks);
self.set_deadline(deadline);
}
}
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